k = gets.to_i
a = [2, 3, 5, 7, 11, 13]
b = [4, 6, 8, 9, 10, 12]
h = {}
a.each { |i|
    b.each { |j|
        ij = i * j
        if h.has_key?(ij) 
            h[ij] += 1
        else
            h[ij] = 1
        end
    }
}
if h.has_key?(k)
    puts h[k] / 36.0
else
    puts "0.00000000000000000"
end